Unfortunately, we don't have an archive from 2007; the broadcast year of these episodes.

But,

• on this 2017 archive, the episodes that you called as second part of season 4 were listed as season 5 episodes 3 and 4, and the seasons 6 and 7 were listed as on our listing.
• on this 2016 archive page, the season 8 was listed as on our listing, and our season 3 is listed as being season 4.
• on this other 2016 archive page, the season 9 was listed as on our listing, and the last 3 episodes of our season 1 are listed as being season 2 (the first one is listed unnumbered).

There is a possibility that a renumbering of the seasons took place in the middle of season 4-5 (between the 2 parts), in which case our listing would be correct. So, we absolutely need to find data from the time of the broadcast to be sure of the original split of the seasons.